Fiber transmission is very mature both in the technical aspect and in the network application aspect, but a wireless manner needs to be used for transmission in many places due to the limitation of landforms. In the case of requiring a large amount of bandwidth, a microwave transmission manner is generally adopted. At present, in markets such as base station backhaul transmission of a mobile cellular system, a metropolitan area network in a transmission network, a digital trunk transmission network of radio and television, a private network (for example, electricity power and military) and large enterprise access network, the microwave transmission is widely applied.
In a microwave transmission communication system, commonly used frequency bands are 1.4 GHz-2.7 GHz, 3 GHz-11 GHz, and 23 GHz-55 GHz, channel bandwidth is from 0.025 MHz to 56 MHz, and a transmission rate may reach hundreds of MBps.
With the increase of service demands, the microwave transmission system needs to develop towards higher-speed transmission communication. Currently, E-Band frequency bands such as 71 GHz-76 GHz and 81 GHz-86 GHz may be used, and the channel bandwidth is 250 MHz. When an ultra wideband is adopted for data transmission, the transmission rate may be up to GBps.
A high frequency band channel is likely to be affected by environmental factors such as the weather. In fine weather, the channel environment is good, and the channel condition is desirable; in awful weather, the channel condition is poor. In order to further improve the transmission efficiency, the Adaptive Modulation (Adaptive Modulation, AM) technology is usually adopted. A high modulation mode is used when the channel condition is desirable, and a low modulation mode is used when the channel condition is poor. When the channel condition varies, in the prior art, the channel environment is not taken into consideration during the adjustment of the transmission power, and too high transmission power may cause a waste of a system gain and meanwhile may interfere with other transmission systems, and even too low transmission power causes service interruption.